In the July issue of Glamour, the "Rock of Ages "star admits to being highly competitive with the "American Idol" host, whom she began dating in 2010. "It gets silly. Ryan and I are very alike," she explains. "When we work out with a trainer, we'll die before we stop, like, to the point where we can't breathe."

Though she's 24 and he's 37, their age difference doesn't bother Hough. As for Seacrest? "He's always joking about it," Hough tells the magazine.

The two first met while Hough was engaged to childhood pal Zach Wilson, also a dancer. "He was a great guy -- I'd known him since I was 9. But I needed to figure myself out more, and so I moved to L.A. and we ended it," Hough says of Wilson. "And actually, he ended up marrying my childhood best friend, and now they have a kid together. It was a little weird when it happened, but they're a great couple!"

The dancer-turned-actress rebounded with country music star Chuck Wicks, 32, who went on to become her partner on "Dancing With the Stars." "While we were dating, we went on Ryan's radio show together. The interview's on YouTube, and I blush when I hear it because Ryan is hitting on me the entire time! At the end, Ryan said something like, 'You guys really have something special!' And I thought to myself, 'He's so full of s--- right now!' When Chuck and I broke up, I wanted to be single. That lasted five months. Then Ryan and I went on a date."

Like Seacrest, who also hosts "E! News" and continues to emcee his daily radio show, Hough is workhorse. "I'm a very anxious person. If I'm not working, I go crazy," she tells Glamour. "I've been lucky in my career. But if I lost everything tomorrow -- and had no money -- I would somehow make it work. I have that survivor mentality because of a lot of stuff that went on in a previous life. I feel like I've had four lives."